Nature 387, 611–617(1997)

The sequence of neurotactin reported in this Letter is identical to that of fractalkine, a CX3C membrane-bound chemokine reported in a Letter by J. F. Bazan et al. in Nature 385, 640–644(1997), published while the paper by Pan et al. was under consideration. A note to this effect in the paper by Pan et al. was inadvertently omitted by Nature.